The present invention relates to sprinkler units, and pertains particularly to a rotary stream sprinkler unit with damping means.
In my prior U.S. Pat. No. 3,854,664, issued Dec. 17, 1974, entitled "SPRINKLER SYSTEMS", I disclose a sprinkler unit which has a rotating head that directs a plurality of rotating streams over an area to be watered. The streams of water are formed in nozzles in the rotating head. The rotating head has inlets to the nozzle on one end, which engages and cooperates with an orifice plate for acting as a valve for controlling communication of pressurized water to the nozzles. A turbine and reduction gear unit drives the head at a controlled velocity.
My U.S. Pat. No. 4,471,908, issued Sept. 18, 1984, entitled "PATTERN SPRINKLER HEAD", discloses a similar sprinkler unit having V-shaped nozzles in a cylindrical rotating head. The nozzle inlet openings cooperate with an orifice in an orifice plate to vary the nozzle openings to the source of pressurized water. This combination delivers streams of water of variable length and volume from the nozzles in the distributor head. The rotating head is driven at a substantially constant velocity or rate of rotation by means of a turbine and reduction drive gearing. Such construction is complex and expensive to manufacture.
In a subsequent application co-pending herewith, a plurality of passages in the unit forms nozzles, which control the stream size and velocity delivered to an open channel distributing head. The streams from the nozzles are directed into a plurality of open channels on a rotating distributor head for forming and distributing the streams.
The rotating head in the above described units is driven by a turbine through a reduction drive gear assembly within the body of the sprinkler unit. These drive units are complex and expensive to manufacture.
Sprinkler heads have been known wherein the distributor head is self-propelling, or more particularly, stream propelled. The sprinkler head is rotated either by streams of water flowing from jets or nozzles in the head, or by blades on the head struck by a stream of water causing it to rotate.
Among the problems of the prior art self-propelled device is that it is difficult to control the velocity of rotation of the head. The velocity of rotation of the head is affected by friction, stream pressure and velocity, and other factors, which ultimately determine the reach or distance that the distributed water travels from the head. The higher the velocity of rotation of the head, the shorter the reach of the streams from the head will be.
One prior art approach to solving this velocity control problem is to provide a damper for the rotor. However, the damper must be inexpensive, reliable and long lasting. The problem of sealing the damper against the high pressure water in the sprinkler unit makes it difficult to mount the damper in the housing. The best known prior art dampers have been located outside the housing, as disclosed in U.S. Pat. No. 4,660,766, granted Apr. 28, 1987 and entitled "ROTARY SPRINKLER HEAD". This approach, however, requires the use of complex and expensive structures external to the housing for supporting the damper.
The present invention is an improvement in the invention in my prior U.S. Pat. No. 4,815,662, issued Mar. 28, 1989, entitled "STREAM PROPELLED ROTARY STREAM SPRINKLER UNIT WITH DAMPING MEANS", which is incorporated herein by reference as though fully set forth. In that patent, I disclose a sprinkler unit, which has a rotating head that is self-propelled and directs a plurality of rotating streams over an area to be watered. The velocity of the rotating head is controlled by means of a damping unit inside the sprinkler housing and connected to the head by a common rotatable shaft.
A nozzle in the housing shapes the stream to the rotating head, and the streams of water directed outward are formed in nozzles in the rotating head. The rotating shaft is mounted in a damper unit housing at the inner end and in a portion of the housing at the outer end. Sealing of the housing around the shaft against fine sand and grit and against water leakage into the damper unit is a major problem. The sealing of the outer journal support of the housing against fine sand, grit, and the like is also a problem.
Some attempts have been made in the past to control the velocity of rotation of the distributor head by some type of damping means. However, these attempts have been unsatisfactory.
Accordingly, it is desirable that an improved rotary stream sprinkler unit be available.